Senate Appropriations Chairman Daniel K. Inouye has died after suffering respiratory problems that kept him in the hospital since Dec. 6.

Inouye was also Senate president pro tem, which by law is a position third in line for the presidency.

Inouye was transfered Dec. 9 to Bethesda from George Washington University hospital, where he had gone Dec. 6 for an examination.

He was seen using oxygen around the Capitol before being admitted to George Washington University hospital. It was explained at the time that because of a misdiagnosis of lung cancer several decades ago, Inouye had part of one of his lungs removed, causing the need for the oxygen treatment. Other news outlets have reported that Inouye may also have suffered from emphysema.

A statement circulated by Inouye’s office late Sunday night said there was “no timetable” for the senator’s release from the hospital. The statement signaled that he had remained “stable” at Walter Reed National Military Medical Center in Bethesda, Md., and that he had been able to communicate with family.

“His family and loved ones are overwhelmed by the outpouring of affection and good wishes for his recovery. We ask that the people of Hawaii and the nation keep the senator in their thoughts and prayers,” spokesman Peter Boylan said in the statement Sunday that prompted some additional concern.

“Unfortunately, he is fighting respiratory complications as work is being done to stabilize his supplemental oxygen requirements,” Boylan said.

A Dec. 10 statement attributed to Inouye said, “For the most part, I am OK. However, I am currently working with my doctors to regulate my oxygen intake. Much to my frustration, while undergoing this process, I have to remain in the hospital for my own safety and to allow the necessary observation.”